The present invention relates generally to laryngoscope blades used to insert tubes into the tracheas of patients during medical procedures. In particular, the present invention is an improved mirror laryngoscope.
Laryngoscopy is a medical procedure in which a laryngoscope blade is inserted into the mouth of a patient to facilitate the physician's visualization of the patient's vocal cords and larynx. This procedure is commonly performed during endotracheal intubation, the insertion of a tube into the trachea of the patient for purposes such as the delivery of oxygen, ventilation, and removal of undesirable objects.
Laryngoscope blades typically include an elongated, generally flat and relatively thin shaft having distal and proximal ends. A small cylindrical member having a diameter greater than the thickness of the shaft extends transversely across the distal end or spatula of the shaft to form a blunt tip. The proximal end of the shaft includes a mount configured to releasably engage a handle. An upper flange extends perpendicularly from one edge of the shaft on the side of the shaft opposite the handle mount. A narrow lower flange extends from the end of the upper flange opposite the shaft, and is generally parallel to the shaft. The shaft and upper and lower flanges are typically fabricated from a single piece of stainless steel or other metal. The handle mount is fabricated as a separate element and welded or otherwise attached to the blade. A lamp is mounted to the upper flange and oriented to direct light toward the distal end of the blade. Electrical leads to the lamp are coupled to contacts on the handle mount through a metal tube. The handle includes a battery pack and electrical contacts that mate with the contacts on the handle mount of the blade.
During laryngoscopy and endotracheal intubation the handle is manipulated to insert the laryngoscope blade into the mouth of the patient. With the help of light provided by the lamp, the physician will visually identify the location of the vocal cords. The distal end of the blade is then used to lift the patient's epiglottis to reveal the cords. A stylet or malleable obturator, an elongated, relatively thin and bendable shaft that retains the shape to which it is bent, is inserted into the endotracheal tube and used to guide the tube past the epiglottis and vocal cords into the patient's trachea. The stylet is then withdrawn from the endotracheal tube and the laryngoscope blade removed from the patient's mouth.
Anatomical variations between patients, such as kyphosis of the cervical spine, an inability to open the mouth or a short mandible, can make laryngoscopy and endotracheal intubation difficult with some patients. There may also be a concern for cervical spine injury, in which case the physician will be reluctant to position the patient's head in the optimal position for laryngoscopy. A variety of different types and sizes of laryngoscopy blades are therefor available to physicians, each especially well suited for use under certain circumstances or with specific anatomical characteristics.
One widely used laryngoscopy blade, commonly known as the Macintosh blade, includes a curved shaft. The curve in the Macintosh blade can, however, make it difficult to visualize the vocal cords during laryngoscopy. To help alleviate this problem, one curved laryngoscope blade, known as the Siker blade, includes a mirror which extends from the upper flange near the midpoint of the shaft. The mirror is polished stainless steel, and can be attached to the flange by a copper jacket to facilitate conduction of the patient's endogenous heat to minimize fogging during use. The Siker blade is inserted into the oral cavity of the patient in the usual manner, with the physician indirectly viewing the vocal cords and other structures at the distal end of the blade by looking into the mirror from the proximal end.
Another mirror laryngoscope blade is disclosed in the Felbarg U.S. Pat. No. 3,643,654. This laryngoscope blade includes two mirrors in the optical path, enabling the physician to see a right-side-up image during laryngoscopy.
Unfortunately, the Siker and Felbarg blades are difficult to use in a variety of circumstances and conditions where the mirror may otherwise be advantageous. For example, these blades can be difficult to place in the mouth of many patients. The blade may also be beyond the vocal cords and into the esophagus before the mirror is even in the patient's mouth. A continuing need therefore exists for mirror laryngoscope blades that can be used on patients having conditions or anatomical characteristics which make laryngoscopy difficult with known blades.